/// <summary>
/// Creates a file stream with the given filename that is deleted when either the
/// stream is closed, or the application is terminated.
/// </summary>
/// <remarks>
/// If the file already exists, it is overwritten without any error (CREATE_ALWAYS).
/// </remarks>
/// <param name="fileName">The full path to the file to create.</param>
/// <returns>A Stream with read and write access.</returns>
public static FileStream CreateTempFile(string fileName)
{
IntPtr hFile = SafeNativeMethods.CreateFileW(
fileName,
NativeConstants.GENERIC_READ | NativeConstants.GENERIC_WRITE,
NativeConstants.FILE_SHARE_READ,
IntPtr.Zero,
NativeConstants.CREATE_ALWAYS,
NativeConstants.FILE_ATTRIBUTE_TEMPORARY |
NativeConstants.FILE_FLAG_DELETE_ON_CLOSE |
NativeConstants.FILE_ATTRIBUTE_NOT_CONTENT_INDEXED,
IntPtr.Zero);
if (hFile == NativeConstants.INVALID_HANDLE_VALUE)
{
NativeMethods.ThrowOnWin32Error("CreateFileW returned INVALID_HANDLE_VALUE");
}
SafeFileHandle sfhFile = new SafeFileHandle(hFile, true);
FileStream stream;
try
{
stream = new FileStream(sfhFile, FileAccess.ReadWrite);
}
catch (Exception)
{
SafeNativeMethods.CloseHandle(hFile);
hFile = IntPtr.Zero;
throw;
}
return(stream);
}
private static bool EnableCompression(string filePath)
{
IntPtr hFile = IntPtr.Zero;
try
{
hFile = SafeNativeMethods.CreateFileW(
filePath,
NativeConstants.GENERIC_READ | NativeConstants.GENERIC_WRITE,
NativeConstants.FILE_SHARE_READ | NativeConstants.FILE_SHARE_WRITE | NativeConstants.FILE_SHARE_DELETE,
IntPtr.Zero,
NativeConstants.OPEN_EXISTING,
NativeConstants.FILE_FLAG_BACKUP_SEMANTICS,
IntPtr.Zero);
if (hFile == NativeConstants.INVALID_HANDLE_VALUE)
{
int dwError = Marshal.GetLastWin32Error();
return(false);
}
ushort cType = NativeConstants.COMPRESSION_FORMAT_DEFAULT;
uint dwBytes = 0;
bool bResult;
unsafe
{
bResult = NativeMethods.DeviceIoControl(
hFile,
NativeConstants.FSCTL_SET_COMPRESSION,
new IntPtr(&cType),
sizeof(ushort),
IntPtr.Zero,
0,
ref dwBytes,
IntPtr.Zero);
}
return(bResult);
}
finally
{
if (hFile != IntPtr.Zero)
{
SafeNativeMethods.CloseHandle(hFile);
hFile = IntPtr.Zero;
}
}
}
/// <summary>
/// Opens a file for streaming. This stream should be read from or written
/// to sequentially for best performance. Random I/O is still permissible,
/// but may not perform as well.
/// This file is created in such a way that is it NOT indexed by the system's
/// file indexer (e.g., Windows Desktop Search).
/// </summary>
/// <param name="fileName">The file to open.</param>
/// <returns>A Stream object that may be used to read from or write to the file, depending on the fileMode parameter.</returns>
public static FileStream OpenStreamingFile(string fileName, FileAccess fileAccess)
{
uint dwDesiredAccess;
uint dwCreationDisposition;
switch (fileAccess)
{
case FileAccess.Read:
dwDesiredAccess = NativeConstants.GENERIC_READ;
dwCreationDisposition = NativeConstants.OPEN_EXISTING;
break;
case FileAccess.ReadWrite:
dwDesiredAccess = NativeConstants.GENERIC_READ | NativeConstants.GENERIC_WRITE;
dwCreationDisposition = NativeConstants.OPEN_ALWAYS;
break;
case FileAccess.Write:
dwDesiredAccess = NativeConstants.GENERIC_WRITE;
dwCreationDisposition = NativeConstants.CREATE_NEW;
break;
default:
throw new InvalidEnumArgumentException();
}
uint dwFlagsAndAttributes =
NativeConstants.FILE_ATTRIBUTE_TEMPORARY |
NativeConstants.FILE_FLAG_SEQUENTIAL_SCAN |
NativeConstants.FILE_ATTRIBUTE_NOT_CONTENT_INDEXED;
IntPtr hFile = SafeNativeMethods.CreateFileW(
fileName,
dwDesiredAccess,
NativeConstants.FILE_SHARE_READ,
IntPtr.Zero,
dwCreationDisposition,
dwFlagsAndAttributes,
IntPtr.Zero);
if (hFile == NativeConstants.INVALID_HANDLE_VALUE)
{
NativeMethods.ThrowOnWin32Error("CreateFileW returned INVALID_HANDLE_VALUE");
}
FileStream stream;
try
{
SafeFileHandle sfh = new SafeFileHandle(hFile, true);
stream = new FileStream(sfh, fileAccess, 512, false);
}
catch
{
SafeNativeMethods.CloseHandle(hFile);
hFile = IntPtr.Zero;
throw;
}
return(stream);
}
